KR20080004537A - Voltage converting apparatus and vehicle - Google Patents

Abstract

A DC/DC converter (30) includes a reactor (L), an IGBT element (TR3), an IGBT element (TR4), a dead time generating part (37), and a DC-CPU (31). The dead time generating part (37) outputs, in accordance with a reference signal of duty ratio (GATEBA), first and second activation signals (GUP,GUN) in which a non-activation interval of a dead time, for which to keep both of the IGBT elements (TR3,TR4) nonconductive, is provided. The DC-CPU (31) corrects the virtual duty ratio, which has been calculated based on a voltage command value (Vfcr), in accordance with a reactor current value (IL) flowing through the reactor (L), and then outputs the reference signal (GATEBA). Preferably, the DC-CPU (31) gradually switches correction values when the reactor current value gets close to a value at which a transition occurs among three states of the reactor current value (IL).

Description

Voltage converter and vehicle {VOLTAGE CONVERTING APPARATUS AND VEHICLE}

The present invention relates to a voltage converter and a vehicle, and more particularly, to a voltage converter provided between two voltage systems and capable of supplying current in both directions, and a vehicle equipped with the voltage converter.

Japanese Patent Laid-Open No. 2004-120844 discloses a control device for a boost converter used in combination with an inverter. The control device operates in response to the difference between the detected output voltage value and the output voltage control value, thereby controlling the duty ratio of the converter switching element by feedback by proportional integral control.

The control device obtains an output power value of the inverter by a calculation circuit, compares the value with a predetermined value by a comparator, and determines a path of the current of the converter, and changes the voltage of the converter according to the determination result. The amount of duty cycle correction is output from the correction circuit to minimize or prevent it.

Recently, electric vehicles, hybrid vehicles, fuel cell vehicles and other similar vehicles have been adopted that adopt an AC motor as a driving source for driving the vehicle and mount therein an inverter device for driving the AC motor.

Some such vehicles mount therein two or more different voltage batteries, such as a high voltage battery for driving a motor and a low voltage battery for auxiliary machinery to propel the vehicle.

Furthermore, when a vehicle equipped with a fuel cell starts to drive, the fuel cell outputs a changing voltage before a stable output is obtained. Accordingly, in order to ensure a stable driving force, it has been studied to combine fuel cells with secondary cells and connect them by a voltage converter for use together.

Both the output voltage of the fuel cell and the output voltage of the secondary battery change depending on the state of the vehicle. Thus, the voltage converter connected therebetween is operated to supply current from the secondary battery to the fuel cell and vice versa in accordance with the power required for the vehicle.

Accordingly, there is a demand for a voltage converter capable of quickly outputting a required voltage according to the acceleration of the vehicle, the inclination of the road, and the like.

Further, Japanese Patent Laid-Open No. 2004-120844 discloses determining an amount of correcting the duty ratio in accordance with the power output from the inverter. However, in a system having a fuel cell connected adjacent to an inverter, the output voltage of the inverter alone may be insufficient to obtain an accurate optimal correction amount.

The present invention has devised a voltage converter capable of facilitating controlling the output voltage and a vehicle provided with the voltage converter.

In summary, the present invention provides a voltage conversion device comprising a control unit for controlling a voltage converter used in combination with an inverter. The control unit includes: detection means for detecting a current passing through the voltage converter; And correction means operable in response to an output received from said detection means for correcting the duty ratio at which said voltage converter can turn on and off a switching element.

The voltage converter preferably provides voltage conversion between a first power node connected to the inverter and a second power node connected to a power storage device.

Preferably, the fuel cell is also connected to the first power node through a rectifying element.

The voltage converter preferably sets the voltage of the first power node higher than the voltage of the second power node when the duty ratio is greater.

The present invention in still another embodiment provides a voltage conversion device comprising a control unit for controlling a voltage converter used in combination with an inverter. The control unit includes a detection unit for detecting a current passing through the voltage converter; And a correction unit operable in response to the output received from said detection means for correcting the duty ratio at which said voltage converter can turn on and off the switching element.

The voltage converter preferably provides voltage conversion between a first power node connected to the inverter and a second power node connected to a power storage device.

Preferably, the fuel cell is also connected to the first power node through a rectifying element.

The voltage converter preferably sets the voltage of the first power node higher than the voltage of the second power node when the duty ratio is greater.

Another embodiment of the present invention provides a reactor; A first switching element operable to couple one end of the reactor with a first power node in response to a first activation signal; A second switching element operable to couple one end of the reactor with a ground node in response to a second activation signal; A first signal operable to output the first and second activation signals provided with an inactivity period corresponding to a dead time preventing both the first and second switching elements from conducting in response to a reference signal for the duty ratio; Dead time generating unit; And a control unit for correcting the temporary duty ratio calculated based on the voltage control value according to the value of the current passing through the reactor to output the reference signal.

The control unit associates the value of the current of the reactor with the three states, and when the value of the current of the reactor approaches the value at which the state transitions, the control unit preferably gradually switches the correction value.

Preferably, the control unit performs proportional integral control based on the deviation between the voltage control value and the output voltage value, and corrects the integral term according to the value of the current of the reactor to correct the temporary duty ratio.

The voltage converter includes: a second dead time generation unit operative in response to the reference signal to output a third activation signal and a fourth activation signal that are activated in synchronization with the second activation signal and the first activation signal; A third switching element operable to couple the other end of the reactor with a second power node in response to the third activation signal; And a fourth switching element operable to couple the other end of the reactor with the ground node in response to the fourth activation signal.

Preferably, the first power node is connected to an inverter for driving a motor, and the second power node is connected to a power storage device.

Preferably, the fuel cell is also connected to the first power node through a rectifying element.

Another embodiment of the present invention, a reactor; A first switching element operable to couple one end of the reactor with a first power node in response to a first activation signal; A second switching element operable to couple one end of the reactor with a ground node in response to a second activation signal; A first signal operable to output the first and second activation signals provided with an inactivity period corresponding to a dead time preventing both the first and second switching elements from conducting in response to a reference signal for the duty ratio; Dead time generating unit; And a control unit for correcting the temporary duty ratio calculated based on the voltage control value according to the value of the current passing through the reactor to output the reference signal.

The control unit associates the value of the current of the reactor with the three states, and when the value of the current of the reactor approaches the value at which the state transitions, the control unit preferably gradually switches the correction value.

Preferably, the control unit performs proportional integral control based on the deviation between the voltage control value and the output voltage value, and corrects the integral term according to the value of the current of the reactor to correct the temporary duty ratio.

The voltage converter includes: a second dead time generation unit operative in response to the reference signal so as to output a third activation signal and a fourth activation signal, which are activated in synchronization with the second activation signal and the first activation signal; A third switching element operable to couple the other end of the reactor with a second power node in response to the third activation signal; And a fourth switching element operable to couple the other end of the reactor with the ground node in response to the fourth activation signal.

The vehicle includes a motor for driving a wheel; An inverter connected to the first power node to drive the motor; And a power storage device connected to the second power node.

The vehicle includes a fuel cell; And a rectifying element connected between the first power node and the fuel cell.

According to the present invention, an output voltage with improved precision can be provided, so that when the current of the reactor has a changed state, the output voltage can converge to the target value in the initial stage.

1 is a view showing the configuration of a vehicle equipped with a voltage converter according to an embodiment of the present invention;

2 is a circuit diagram showing a detailed configuration of the DC / DC converter 30 of FIG.

3 is a diagram for illustrating how the current through the reactor changes when the duty ratio of the switching element is less than 50%;

4 is a diagram illustrating how the current through the reactor changes when the duty ratio of the switching element is greater than 50%;

5 is a waveform diagram for illustrating that the current of the reactor is classified into three states;

FIG. 6 is an operation waveform diagram showing the relationship between the change in the current of the reactor and the reference signal GATEBA in the state A shown in FIG. 5;

FIG. 7 is an operation waveform diagram showing the relationship between the change in the current of the reactor and the reference signal GATEBA in the state C shown in FIG. 5;

FIG. 8 is an operating waveform diagram showing a relationship between a change in current of a reactor and a reference signal GATEBA in the state B shown in FIG. 5;

9 is a block diagram showing the configuration of the DC-CPU 31 shown in FIG. 2;

10 is a flowchart showing the structure of processing performed by the DC-CPU 31;

11 is a diagram showing a relationship between a reactor current and a dead time correction value when the reactor current is negative;

Fig. 12 shows the relationship between the reactor current and the dead time correction value when the reactor current is positive;

FIG. 13 is a block diagram showing the configuration of a DC-CPU 31A replacing the DC-CPU 31 of FIG. 2 in the second embodiment; FIG.

14 is a flowchart showing a structure of processing performed by the DC-CPU 31A; And

15 is a diagram illustrating an example of switching the integral term gain.

Hereinafter, the present invention will be described in more detail with reference to the drawings. In the drawings, the same or corresponding elements are represented the same and will not be described repeatedly.

General composition of the vehicle

1 is a diagram illustrating a configuration of a vehicle in which a voltage converter according to an embodiment of the present invention is mounted. As an example, the vehicle is shown as a fuel cell vehicle. However, the vehicle is not limited to this. The present invention is also applicable to electric vehicles and hybrid vehicles.

Referring to FIG. 1, the vehicle operates so that the synchronous motor 61 connected to the wheels 63L and 63R serves as a driving power source. The synchronous motor 61 is driven by the power supply system 1. The power supply system 1 converts into three-phase alternating current by the inverter 60 and outputs a direct current supplied to the synchronous motor 61. The synchronous motor 61 also functions as a power generator during braking.

The power supply system 1 is composed of a fuel cell 40, a battery 20, a DC / DC converter 30, and the like. The fuel cell 40 is a device that generates electric power by an electrochemical reaction of hydrogen and oxygen. As an example, a solid polymer battery may be used. However, the fuel cell 40 is not limited to this. This may be implemented by phospho-fuel cells, melt-carbonate fuel cells or various types of fuel cells. In power generation, hydrogen gas is produced by modifying alcohol or similar source materials. In the present embodiment, a stack for generating power and a reformer for generating fuel gas may be included, which is called a fuel cell 40. Note that the reformer may be replaced by a configuration example using a hydrogen storage alloy, a hydrogen cylinder, or the like to essentially occlude hydrogen gas.

The battery 20 is a rechargeable / dischargeable secondary battery, and a nickel metal hydride battery may be used as an example. Furthermore, various types of secondary batteries are also applicable. Furthermore, the battery 20 may be replaced by a chargeable and dischargeable power storage device other than a secondary battery such as a capacitor.

The fuel cell 40 and the battery 20 are connected in parallel to the inverter 60. The circuit from the fuel cell 40 to the inverter 60 is provided with a diode 42 for preventing the current flowing from the battery 20 or generated by the synchronous motor 61 to reverse again. Appropriate use of the power of each of the power supplies connected in parallel involves controlling the relative difference in voltage between them. To this end, this embodiment provides a DC / DC converter 30 between the battery 20 and the inverter 60. The DC / DC converter 30 is a DC voltage converter. The DC / DC converter 30 receives a DC voltage from the battery 20, adjusts the received DC voltage, and outputs the adjusted voltage to the inverter 60, and includes a fuel cell 40 or a motor ( Receives a DC voltage from 61, adjusts the received DC voltage, and outputs the adjusted voltage to the battery (20). The DC / DC converter 30 in charge of this function allows the battery 20 to be charged and discharged.

Between the battery 20 and the DC / DC converter 30, the vehicle auxiliary machinery 50 and the FC auxiliary machinery 51 are connected. In other words, the battery 20 serves as a power source for these auxiliary machinery. Vehicle auxiliary machinery 50 is a variety of power equipment used in driving the vehicle. This includes lighting equipment, air conditioners, hydraulic pumps and the like. The FC auxiliary machine 51 is a variety of power equipment used in the operation of the fuel cell 40. This includes pumps used to supply fuel gas, source materials to be modified, heaters to adjust the temperature of the reformer, and the like.

Each component described above is operated by being controlled by a control unit 10 configured as a microcomputer internally containing a CPU, a RAM and a ROM. The control unit 10 controls the inverter 60 to switch to output the three-phase alternating current corresponding to the required driving force to the synchronous motor 61. In order to supply power corresponding to the required driving force, the operation of the fuel cell 40 and the operation of the DC / DC converter 30 are controlled.

In order to implement such control, the control unit 10 detects, for example, an accelerator pedal sensor 11, a state of charge (SOC) sensor 21 for detecting SOC of the battery 20, and a gas flow rate of the fuel cell 40. Signals are received from various sensors including a flow rate sensor 41 and a vehicle speed sensor 62 for detecting a vehicle speed. Although not shown, the control unit 10 is also connected to many other types of sensors.

FIG. 2 is a circuit diagram showing the detailed configuration of the DC / DC converter 30 of FIG. Note that for ease of operation, FIG. 2 also shows the configuration of a portion of the portion around the DC / DC converter 30.

Referring to FIG. 2, the vehicle has a battery 20, a smoothing capacitor 6 connected between terminals of the battery 20, an inverter 60, a motor 61 driven by the inverter 60, and a series circuit. A diode 42 and a fuel cell 40 connected to supply a DC voltage to the inverter and a smoothing capacitor 14 connected between the power terminals of the inverter are provided. Diode 42 is a protective device for preventing current from flowing into fuel cell 40.

The vehicle also has a voltage sensor 22 for detecting the voltage VB of the battery 20 therein, a current sensor 23 for detecting the current IB flowing to the battery 20, and a voltage VINV of the inverter. The voltage sensor 44 for detecting the voltage, the current sensor 43 for detecting the current (IINV) flowing in close proximity to the inverter, and the DC / performing voltage conversion between the voltage (VB) of the battery and the voltage (VINV) of the inverter. The DC converter 30 was mounted.

The DC / DC converter 30 includes a first arm connected between the terminals of the battery 20, a second arm connected between the power terminals of the inverter 60, and a reactor connected between the first arm and the second arm. L).

The first arm is connected in parallel between the IGBT elements TR1 and TR2 connected in series between the positive electrode and the negative electrode of the battery 20, the diode D1 connected in parallel to the IGBT element TR1, and the IGBT element TR2 in parallel. And a diode D2.

The IGBT element TR1 includes a collector connected to the positive electrode of the battery 20 and an emitter connected to the node N1. The diode D1 is connected so that the direction from the node N1 toward the positive electrode of the battery 20 becomes the forward direction.

The IGBT element TR2 includes a collector connected to the node N1 and an emitter connected to the negative electrode of the battery 20. The diode D2 is connected such that the direction from the negative electrode of the battery 20 to the node N1 is the forward direction.

The second arm includes the IGBT elements TR3 and TR4 connected in series between the positive and negative power terminals of the inverter, the diode D3 and the IGBT element TR4 connected in parallel to the IGBT element TR3. And a diode D4 connected in parallel.

The IGBT element TR3 has a collector connected to the positive power terminal of the inverter 60 and an emitter connected to the node N2. The diode D3 is connected such that the direction from the node N2 toward the positive power supply terminal of the inverter 60 becomes the forward direction.

The IGBT element TR4 has a collector connected to the node N2 and an emitter connected to the negative power supply terminal of the inverter 60. The diode D4 is connected so that the direction from the negative power supply terminal of the inverter 60 to the node N2 is the forward direction.

Reactor L is connected between node N1 and node N2.

The voltage VB of the battery 20 and the voltage output by the fuel cell 40 may each assume ranges that partially overlap each other. For example, the battery is embodied as a nickel metal hydride battery, the power supply voltage of which is for example changed within the range of 200V to 300V. On the other hand, the fuel cell 40 outputs a voltage that varies, for example, in the range of 240V to 400V for illustrative purposes. As such, the voltage of the battery 20 may be higher or lower than the output from the fuel cell 40. Accordingly, the DC / DC converter 30 is configured to have a first arm and a second arm, as described above. This configuration enables up / down voltage conversion from battery 20 to inverter 60 and up / down voltage conversion from inverter 60 to battery 20.

The DC / DC converter 30 includes the DC-CPU 31, the buffer 32, the inversion buffers 34, 35, 36, 38, and 39, the dead time generating units 33 and 37, and the reactor L. It further comprises a current sensor SE for detecting the value of the current (IL).

The DC-CPU 31 is operated to output a signal GATEBA, which serves as a reference for the duty ratio for switching the converter, in response to the voltage control value Vfcr and the current value IL. The signal GATEBA is transmitted to the dead time generation unit 33 by the buffer 32. The dead time generation unit 33 delays the rise of the output signal so that the dead time provides two complementary output signals having respective active periods therebetween. In dead time, both output signals are deactivated.

The dead time generation unit 33 outputs complementary signals input to the inversion buffers 34 and 35, respectively. The inversion buffer 34 outputs the gate signal MUP to the IGBT element TR1. The inversion buffer 35 outputs the gate signal MDN to the IGBT element TR1.

Further, the signal GATEBA is also transmitted to the dead time generation unit 37 by the inversion buffer 36. The dead time generation unit 37 delays the rise or fall of the input signal so that the dead time is provided therebetween, providing two complementary output signals having respective active periods. In dead time, both output signals are deactivated.

The dead time generation unit 37 outputs complementary signals input to the inversion buffers 38 and 39. The inversion buffer 38 outputs the gate signal GUP to the IGBT element TR3. The inversion buffer 39 outputs the gate signal GUN to the IGBT element TR4.

FIG. 3 is a diagram illustrating how the current through the reactor changes when the duty ratio of the switching element is less than 50%.

4 is a diagram illustrating how the current through the reactor changes when the duty ratio of the switching element is greater than 50%.

Here, "duty ratio" is expressed as Ton / (Ton + Toff), where Ton represents the on time of the switching element, Toff represents the off time of the switching element.

Furthermore, while the reactor current has a slope determined by ΔI / ΔT = V / L, FIGS. 3 and 4 show the reactor current IL for the case where the voltage at the inlet and outlet of the converter is the same for ease of understanding. ).

As shown in FIG. 3, when the duty ratio D of the IL reference pulse is less than 50%, the reactor current IL gradually decreases. In contrast, as shown in FIG. 4, when the duty ratio D of the IL reference pulse is greater than 50%, the current IL of the reactor gradually increases.

When the battery 20 of FIG. 2 is discharged, the IGBT elements TR1 and TR4 are controlled to be turned on to store energy in the reactor L. Subsequently, when both of the IGBT elements TR1 and TR4 are controlled to be turned off, the energy stored in the reactor L is discharged through the current path of the diode D2 → reactor L → diode D3.

This causes the power supplied from the battery 20 to drive the inverter 60 to rotate the motor 61. Synchronized therewith, the IGBT elements TR2 and TR3 are controlled to conduct, thereby reducing the resistive force to reduce losses in the diodes D2 and D3. However, it should be noted that when the IGBT device is switched to turn off, it is turned off with a delay, thereby providing a gate control signal with dead time.

Given the reference signal GATEBA, which is generated as the DC-CPU 31 of FIG. 2, PWM control is used to generate a signal to drive the gate of the IGBT device, for example to delay a command to turn on the device. A configuration is added to avoid the risk of shorting of the upper and lower arms and to avoid such shorting, the upper and lower arms having IGBT elements that are both turned off during a time period called dead time.

Although not shown, the motor 61 is connected to the wheels via a reduction gear. Accordingly, the battery 20 may be operated when the motor 61 is operated within a power range high enough that the fuel cell 40 alone cannot provide power that satisfies the required power; It is discharged when the vehicle stops, runs with a small load, or when the efficiency of the fuel cell 40 is driven within a low range.

When the battery 20 of FIG. 2 is charged, the IGBT elements TR2 and TR3 are controlled to be turned on to store energy in the reactor L. Subsequently, if both of the IGBT elements TR2 and TR3 are controlled to be turned off, the energy stored in the reactor L is discharged through the current path of the diode D4? Reactor L? Diode D1.

Thus, the battery 20 may include a case in which the battery 20 has a reduced SOC, and the fuel cell 40 also has a margined output; Alternatively, the vehicle being driven is braked, and the motor 61 is charged when the motor 61 provides a regenerative operation to restore electrical energy and store it in the battery 20.

By this operation, the DC power generated in the fuel cell 40 is supplied, or the AC power generated in the motor 61 by the regenerative operation is converted into the DC power in the inverter 60, thereby replacing the battery 20. Supplied to charge.

Charging of the battery 20 is also done with dead time introduced to prevent the upper and lower arms from shorting out.

5 is a waveform diagram for illustrating that the current of the reactor is classified into three states.

Referring to FIG. 5, state A is a state in which the current IL of the reactor is constantly negative for one switching cycle. Note that if the reactor has a current in the direction indicated by the arrow of the current IL of the reactor shown in Fig. 2, the reactor has a current in the positive direction. In other words, state A is a state in which the battery 20 is charged from the fuel cell 40 or the inverter 60.

State C is a state in which the reactor's current IL is constantly positive for one switching cycle. In other words, state C is a state in which the battery 20 is discharged to the inverter 60.

State B is a state in which, during one switching cycle, the current IL of the reactor has a maximum value Imax having a positive value and a minimum value Imin having a negative value. In other words, state B is a state in which the current for charging the battery 20 and the current for discharging the battery 20 almost cancel each other.

FIG. 6 is an operation waveform diagram illustrating a relationship between a change in current of a reactor and a reference signal GATEBA in the state A shown in FIG. 5.

2 and 6, the reference signal GATEBA output from the DC-CPU 31 having the dead time added by the dead time generating units 33 and 37 is consequently shown in the waveform diagram of FIG. As described above, the IGBT elements TR1 to TR4 are turned on and off.

More specifically, the IGBT elements TR1 and TR4 that are turned on at and in response to the time t1 at which the reference signal GATEBA falls are turned off or deactivated, and the dead time Tdt1 has elapsed or the time t3 is reached. At this time, the turned off IGBT elements TR2 and TR3 are turned on or activated.

Subsequently, at the time t4 at which the reference signal GATEBA rises and in response thereto, the turned-on IGBT elements TR2 and TR3 are turned off or deactivated, and when the dead time Tdt2 elapses or the time t6 is reached, The turned off IGBT elements TR1 and TR4 are turned on or activated.

Note that the IGBT elements TR1 to TR4 each have diodes D1 to D4 connected in parallel thereto. This allows current to flow even during dead time in the forward direction of the diode.

In state A, the current IL of the reactor flows negative, i.e. from node N2 in FIG. Accordingly, when all of the IGBT elements TR1 to TR4 are turned off, that is, at dead time, the diodes D1 and D4 become conductive.

In other words, during the time t6 to t7 in which the IGBT elements TR1 and TR4 are conducted, plus the dead time Tdt1 and Tdt2, that is, for the time t4 to t9, the reactor current IL increases for one cycle, and the reactor The current IL of decreases for one cycle only during the time t3 to t4, i.e. only when the IGBT elements TR2 and TR3 are conducted.

As such, if the reference signal GATEBA has a duty ratio of 50%, the state IL of the reactor in the state A will tend to increase gradually.

FIG. 7 is an operation waveform diagram illustrating a relationship between a change in current of a reactor and a reference signal GATEBA in the state C shown in FIG. 5.

In FIG. 7, the IGBT elements TR1 to TR4 are turned on and off and the reference signal GATEBA is similar to that of FIG. 6. Accordingly, description will not be repeated.

2 and 7, in state C, the current IL of the reactor flows positive, that is, from node N1 to node N2 in FIG. 2. Accordingly, when all of the IGBT elements TR1 to TR4 are turned off, that is, at the dead time, the diodes D2 and D3 become conductive.

In other words, during the conduction time of the IGBT elements TR2 and TR3 of t3 to t4 and the total time of the dead time Tdt1 and Tdt2, that is, for the time t1 to t6, the reactor current IL decreases for one cycle, The current IL of the reactor increases for one cycle only during times t6 to t7, i.e. only when the IGBT elements TR1 and TR4 are conductive.

As such, if the reference signal GATEBA has a duty ratio of 50%, the state IL of the reactor in the state C will tend to decrease gradually.

FIG. 8 is an operating waveform diagram illustrating a relationship between a change in current of a reactor and a reference signal GATEBA in the state B shown in FIG. 5.

In FIG. 8, how the IGBT elements TR1 to TR4 are turned on and off and the reference signal GATEBA are similar to those of FIG. 6. Accordingly, description will not be repeated.

Referring to FIGS. 2 and 8, in state B, a time period in which the current IL of the reactor flows positive, that is, from the node N1 of FIG. 2 to the node N2, and the current IL of the reactor is negative, that is, of FIG. 2. The time period flowing from node N2 to node N1 is repeated.

In this case, during the conduction time of the IGBT elements TR2 and TR3 of t3 to t4 and the total time of the dead time Tdt1, that is, for the time t1 to t4, the reactor current IL decreases for one cycle, and the IGBT element During the conduction time of (TR1, TR4) and the total time of dead time (Tdt2), that is, for time t4 to t7, the current IL of the reactor increases for one cycle.

As such, if the reference signal GATEBA has a duty ratio of 50% and the dead times Tdt1 and Tdt2 are the same, there will be a tendency to maintain the current state of the reactor current IL in state B.

Therefore, as described with reference to FIGS. 6 to 8, the duty ratio of the reference signal GATEBA and the duty at which the current actually increases / decreases in the reactor depend on the current state of the reactor.

As such, for precise control, it is necessary to correct the duty ratio of the reference signal GATEBA according to the current state of the reactor.

More specifically, in state A, it is necessary to correct the duty ratio of the reference signal GATEBA smaller than the target, and in state C, it is necessary to correct the duty ratio of the reference signal GATEBA larger than the target.

First embodiment

9 is a block diagram showing the configuration of the DC-CPU 31 shown in FIG.

Referring to Fig. 9, the DC-CPU 31 is a calculation unit 72 for calculating a deviation? Vfc between the voltage control value Vfcr and the voltage value VINV of the inverter, and a processing unit for differentiating the deviation? Vfc. (74), an arithmetic unit 76 that multiplies the output of the processing unit 74 by the derivative term KdV, a processing unit 80 that integrates the deviation? Vfc, and an output of the integral term gain KiV by the output of the processing unit 80 The calculation unit 82 includes a calculation unit 78 that multiplies the deviation? Vfc by the proportional weight term KpV, and a calculation unit 84 that calculates the sum of the outputs of the calculation units 76, 82, and 84. The calculating unit 84 outputs the sum signal Vfc.

The DC-CPU 31 also receives the voltage control signal Vfcr and the voltage value VB of the battery, and calculates and outputs Vfcr / (VB + Vfcr) as the voltage value Vfcreq, Receives the current IL of the reactor from the current sensor SE of FIG. 2, determines which one of states A to C of FIG. 5 is present, and the duty ratio by an amount corresponding to the dead time corresponding to the determined state. A dead time correction unit 90 for selecting a value for correcting the voltage, an addition processing unit 88 for adding together the output of the dead time correction unit 90, the voltage value Vfc and the voltage value Vfcreq to output the voltage value V1, and the voltage. And a PWM processing unit 92 which receives the value V1 and outputs a reference signal GATEBA.

The dead time correction unit 90 performs a process for outputting voltage values of -36 V, 5.4 V, and 42.8 V, respectively, as correction values, for states A, B, and C, respectively.

The PWM processing unit 92 supplies a signal GATEBA indicating a timing serving as a switching reference corresponding to the voltage value V1 provided as a result of the addition provided by the adding processing unit 88, in the buffer 32 of FIG. Output to the inversion buffer 36.

10 is a flowchart showing the structure of a process performed by the DC-CPU 31. This process is executed from the main routine of the control for each predetermined time or whenever a predetermined condition is established.

Referring to FIG. 10, when the process is started, initially, at step S1, the DC-CPU 31 obtains the current value IL of the reactor output from the current sensor SE of FIG. 2, and the current of the reactor. Detects which of the states A to C of FIG.

More specifically, while the current value IL increases / decreases for one cycle, its peak value is measured. If Imax <0, it is determined that the current of the reactor has state A. If Imin> 0, it is determined that the current in the reactor has state C. If Imin <0 <Imax, it is determined that the current of the reactor has state B.

Then, in step S2, the dead time correction value is calculated. For example, for states A, B, and C, voltage values of -36V, 5.4V, and 42.8V are provided as correction values, respectively, because before input to the PWM processing unit 92 of FIG. This is because the duty ratio of the reference signal GATEBA is calculated together with the corresponding voltage value. When time is used as a reference for the expression and Tdt1 = Tdt2 = Tdt, from FIGS. 6, 8 and 7, for states A, B, and C, + Tdt, 0, and -Tdt are reference signals GATEBA, respectively. Values for correcting the duty ratio of (ie, dead time correction values). The process then proceeds to step S3.

In step S3, a feedforward term (FF term) and a feedback term (FB term) are initially calculated. The FF term is obtained by calculating Vfcr / (VB + Vfcr). The FB term is obtained by performing a PID process on the deviation? Vfc between the voltage control value Vfcr and the voltage value VINV of the inverter. Then, the FF term + the FB term + the dead time correction value are calculated to obtain the voltage value V1 of FIG. 9, and a reference signal GATEBA having a duty ratio corresponding to the voltage value V1 is obtained.

When step S3 is completed, control returns to the main routine. By this process, an output voltage with improved precision can be provided, and if the current of the reactor has a changed state, the output voltage can be converged to the target value in the initial stage.

Exemplary Modifications of the First Embodiment

In the first embodiment, a dead time correction value corresponding to one of the three current states of the reactor is selected and determined accordingly. However, if the current of the reactor is transferred and changed from one state to another state, there is still room for improvement in voltage controllability.

More specifically, if the current of the reactor changes from state A to state B and then to state C, as shown in Fig. 5, the dead time correction value is suddenly changed suddenly when state A switches to state B. Switching may entail requiring time before a stable output voltage is obtained.

11 shows the relationship between the reactor current and the dead time correction value when the reactor current is negative.

12 shows the relationship between the reactor current and the dead time correction value when the reactor current is positive.

If the current of the reactor has a maximum value Imax <0 for one cycle, as shown in Fig. 11, in the range of Imax <-I1, the dead time correction value ΔT is fixed at -Tdt, and -I1 <Imax < In the range of 0, the dead time correction value DELTA T gradually changes from -Tdt to zero.

In contrast, if the current of the reactor has a minimum value Imin> 0 for one cycle, as shown in FIG. 12, in the range of Imin> I2, the dead time correction value ΔT is fixed at + Tdt, and 0 <Imin In the range of <I2, the dead time correction value DELTA T gradually changes from 0 to + Tdt.

In other words, in FIG. 2, the DC / DC converter 30 operates to couple one end of the reactor L with the first power node of the inverter in response to the reactor L and the first activation signal GUP. Element TR3, an IGBT element TR4, dead time generation unit 37 and DC-CPU 31 which operate to couple one end of reactor L with a ground node in response to second activation signal GUN. It includes.

The dead time generation unit 37, in response to the reference signal GATEBA for the duty ratio, has first and second periods having an inactivity period corresponding to dead time for preventing both of the IGBT elements TR3 and TR4 from conducting. Operate to output activation signals GUP and GUN. The DC-CPU 31 corrects the temporary duty ratio calculated based on the voltage control value Vfcr according to the current value IL of the reactor passing through the reactor L, and outputs a reference signal GATEBA. The DC-CPU 31 associates the current value IL of the reactor with the three states, and when the current value of the reactor approaches a value at which one state transitions to another state, the DC-CPU 31 is connected to FIGS. The correction value is gradually switched according to the maps shown in FIG. 12.

The reference signal GATEBA having the duty ratio corrected by the dead time correction value also enables smooth and steady voltage control when the current of the reactor is transitioned to change from one state to another.

Second embodiment

In the second embodiment, the DC-CPU 31 is replaced with the DC-CPU 31A.

FIG. 13 is a block diagram showing the configuration of a DC-CPU 31A that replaces the DC-CPU 31 of FIG. 2 in the second embodiment.

Referring to Fig. 13, the DC-CPU 31A is a calculation unit 72 for calculating a deviation? Vfc between the voltage control value Vfcr and the voltage value VINV of the inverter, and a processing unit for differentiating the deviation? Vfc. (74), an arithmetic unit 76 that multiplies the output of the processing unit 74 by the derivative term KdV, a processing unit 80 that integrates the deviation? Vfc, and an output of the integral term gain KiV by the output of the processing unit 80 A calculating unit 82A, a calculating unit 78 that multiplies the deviation? Vfc by a proportional term KpV, and a calculating unit 84 that calculates the sum of the outputs of the calculating units 76, 82, and 84. The calculating unit 84 outputs the sum signal Vfc. The calculating unit 82A receives the current value IL of the reactor from the current sensor SE of FIG. 2, determines which one of the states A to C of FIG. 5, and integrates the term to correspond to the determined state. Increase / decrease gain

The DC-CPU 31A also receives the voltage control signal Vfcr and the voltage value VB of the battery, and calculates and outputs Vfcr / (VB + Vfcr) as the voltage value Vfcreq, And an addition processing unit 88A that adds the voltage value Vfc and the voltage value Vfcreq together to output the voltage value V1A, and a PWM processing unit 92 which receives the voltage value V1A and outputs a reference signal GATEBA.

The PWM processing unit 92 supplies a signal GATEBA indicating a timing serving as a switching reference corresponding to the voltage value V1 provided as a result of the addition provided by the adding processing unit 88, in the buffer 32 of FIG. Output to the inversion buffer 36.

14 is a flowchart showing the structure of a process performed by the DC-CPU 31A. This process is called for execution from the main routine of the control for each predetermined time or whenever a predetermined condition is established.

Referring to FIG. 14, when the process is started, the DC-CPU 31A initially acquires the current value IL of the reactor output from the current sensor SE of FIG. 2 in step S11, and the current of the reactor. Detects which of the states A to C of FIG.

More specifically, while the current value IL increases / decreases for one cycle, its peak value is measured. If Imax <0, it is determined that the current in the reactor has state A. If Imin> 0, it is determined that the current in the reactor has state C. If Imin <0 <Imax, it is determined that the current in the reactor has state B.

Then, in step S12, a determination is made as to whether or not the current IL of the reactor has a state different from that obtained when it was sampled immediately before. More specifically, it is detected whether the state transitions A → B, B → C or C → B, B → A have occurred among the states A-C in FIG.

In step S12, if the current of the reactor has a changed state, the process proceeds to step S13, where the integral term gain is increased / decreased for a predetermined time period, because the PID control is executed, corresponding to the dead time. This is because the integral term gain is subjected to duty ratio correction as much as possible, so that the integral term gain is immediately matched to the changed state of the reactor current before the changed state of the reactor current is detected.

15 shows an example of switching the integral term gain.

Referring to Figure 15, the horizontal axis represents the current of the battery corresponding to the state of the current of the reactor. The vertical axis represents the corrected integral term gain. If the current of the battery is negative, i.e., the battery is charged, the integral term gain is -60V. If the current of the battery is positive, i.e. when the battery is discharged, the integral term gain is + 30V. If the battery current is about zero, the integral term gain is -10V.

As can be seen in FIG. 5, if the current of the battery is positive, the current of the reactor has a state corresponding to state C. As can be seen in FIG. 5, if the current of the battery is negative, the current of the reactor is Note that if there is a state corresponding to state A, and the current of the battery is about zero, the current of the reactor has a state corresponding to state B. As described above, even when the current sensor SE is not provided to the reactor L, the general control of the duty ratio correction is made possible by measuring the current IB of the battery.

Referring back to FIG. 14, when step S13 ends, the process proceeds to step S14. The process also proceeds to step S14 if no changed state of reactor current is detected in step S12.

In step S14, a feedforward term (FF term) and a feedback term (FB term) are initially calculated. The FF term is obtained by calculating Vfcr / (VB + Vfcr). The FB term is obtained by performing a PID process on the deviation? Vfc between the voltage control value Vfcr and the voltage value VINV of the inverter. The PID process has an integral term gain that is increased / decreased as needed. Then, the FF term + the FB term are calculated to obtain the voltage value V1A of FIG. 13, and a reference signal GATEBA having a duty ratio corresponding to the voltage value V1A is obtained.

When step S14 is completed, the process proceeds to step S15 where control returns to the main routine. This process causes the output voltage to converge to the target value at an early stage if the current in the reactor has changed.

It is to be understood that the examples disclosed herein are illustrative and not limited to any embodiment. The scope of the present invention is limited to the items of the claims rather than the detailed description above, and is intended to include any modifications within the scope and technical spirit equivalent to the claims.

Claims (20)

In the voltage conversion device comprising a control unit for controlling a voltage converter used in combination with the inverter 60, The control unit, Detection means (SE) for detecting a current passing through the voltage converter; And Characterized in that the voltage converter comprises correction means (31 to 39) which operate in response to the output received from the detection means (SE) to correct the duty ratio for turning on and off the switching element. Voltage converter. The method of claim 1, The voltage converter, characterized in that for providing a voltage conversion between the first power node connected to the inverter (60) and the second power node connected to the power storage device (20). The method of claim 2, A voltage conversion device, characterized in that the fuel cell (40) is also connected to the first power node through a rectifying element (42). The method of claim 2, And the voltage converter sets the voltage of the first power node higher than the voltage of the second power node when the duty ratio is greater. In the voltage conversion device comprising a control unit for controlling a voltage converter used in combination with the inverter 60, The control unit, A detection unit (SE) for detecting a current passing through the voltage converter; And And a correction unit (31 to 39) operable in response to the output received from the detection means (SE) to correct the duty ratio at which the voltage converter can turn on and off the switching element. Voltage converter. The method of claim 5, The voltage converter, characterized in that for providing a voltage conversion between the first power node connected to the inverter (60) and the second power node connected to the power storage device (20). The method of claim 6, A voltage conversion device, characterized in that the fuel cell (40) is also connected to the first power node through a rectifying element (42). The method of claim 6, And the voltage converter sets the voltage of the first power node higher than the voltage of the second power node when the duty ratio is greater. In the voltage converter, Reactor L; A first switching element TR3 operable to couple one end of the reactor L with a first power node in response to a first activation signal GUP; A second switching element TR4 operable to couple one end of the reactor L with a ground node in response to a second activation signal GUN; In response to the reference signal GATEBA for the duty ratio, the first and second activations provided with an inactivity period corresponding to a dead time for preventing both of the first and second switching elements TR3 and TR4 from conducting. A first dead time generating unit 37 operative to output signals GUP and GUN; And And a control unit 31 for correcting the temporary duty ratio calculated based on the voltage control value according to the value of the current IL passing through the reactor L to output the reference signal. Voltage converter. The method of claim 9, The control unit 31 associates the value of the current of the reactor with the three states, and when the value of the current of the reactor approaches the value at which the state transitions, the control unit 31 gradually switches the correction value. Voltage converter, characterized in that. The method of claim 9, The control unit 31 performs proportional integral control based on the deviation between the voltage control value and the output voltage value, and corrects the integral term according to the value of the current of the reactor to correct the temporary duty ratio. Voltage converter. The method of claim 9, A second operation in response to the reference signal to output a third activation signal MUP and a fourth activation signal MUN, which are activated in synchronization with the second activation signal GUN and the first activation signal GUP, respectively. 2 dead time generating unit 33; A third switching element TR1 operable to couple the other end of the reactor L with a second power node in response to the third activation signal MUP; And And a fourth switching element (TR2) operative to couple the other end of the reactor (L) with a ground node in response to the fourth activation signal (MUN). The method of claim 12, The first power node is connected to an inverter (60) for driving a motor, the second power node is a voltage conversion device, characterized in that connected to the power storage device (20). The method of claim 13, A voltage conversion device, characterized in that the fuel cell (40) is also connected to the first power node through a rectifying element (42). In the vehicle, Reactor L; A first switching element TR3 operable to couple one end of the reactor L with a first power node in response to a first activation signal GUP; A second switching element TR4 operable to couple one end of the reactor L with a ground node in response to a second activation signal GUN; In response to the reference signal GATEBA for the duty ratio, the first and second activations provided with an inactivity period corresponding to a dead time for preventing both of the first and second switching elements TR3 and TR4 from conducting. A first dead time generating unit 37 operative to output signals GUP and GUN; And And a control unit 31 for correcting the temporary duty ratio calculated based on the voltage control value according to the value of the current IL passing through the reactor L to output the reference signal. Vehicle comprising a. The method of claim 15, The control unit 31 associates the value of the current of the reactor with the three states, and when the value of the current of the reactor approaches the value at which the state transitions, the control unit 31 gradually switches the correction value. Vehicle characterized in that. The method of claim 15, The control unit 31 performs proportional integral control based on the deviation between the voltage control value and the output voltage value, and corrects the integral term according to the value of the current of the reactor to correct the temporary duty ratio. Vehicle. The method of claim 15, The voltage converter, A second operation in response to the reference signal to output a third activation signal MUP and a fourth activation signal MUN, which are activated in synchronization with the second activation signal GUN and the first activation signal GUP, respectively. 2 dead time generating unit 33; A third switching element TR1 operable to couple the other end of the reactor L with a second power node in response to the third activation signal MUP; And And a fourth switching element (TR2) operative to couple the other end of the reactor (L) with a ground node in response to the fourth activation signal (MUN). The method of claim 18, A motor 61 for driving wheels; An inverter 60 connected to the first power node to drive the motor; And Vehicle further comprises a power storage device (20) connected to the second power node. The method of claim 19, Fuel cell 40; And Vehicle further comprises a rectifying element (42) connected between the first power node and the fuel cell (40).

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